My sons 07 380 sx (used to be mine) has a problem with the srs/airbag warning light.
For no apparent reason it just came on & stayed on.
We checked the connectors under the seats & they all looked OK. So we unplugged them & reconnected just to be sure but it didn't fix the problem.
It says in the manual that faulty seat-belt tensioners can cause the light to come on too but I don't know how to check those...

Can the SRS be reset (DIY) or is it a visit to the Mitsubishi Dealer?

Its not something I would do DIY personally

I would pop down to the dealer Safety is PARAMOUNT

only a dealer with a mut3 can clear an SRS light.